//------------------------------------------------------------------------------
// trees.c -- output deflated data using Huffman coding
// Copyright (C) 1995-2017 Jean-loup Gailly
// detect_data_type() function provided freely by Cosmin Truta, 2006
// For conditions of distribution and use, see copyright notice in zlib.h
//
//------------------------------------------------------------------------------
//  ALGORITHM
//
//      The "deflation" process uses several Huffman trees. The more
//      common source values are represented by shorter bit sequences.
//
//      Each code tree is stored in a compressed form which is itself
// a Huffman encoding of the lengths of all the code strings (in
// ascending order by source values).  The actual code strings are
// reconstructed from the lengths in the inflate process, as described
// in the deflate specification.
//
//  REFERENCES
//
//      Deutsch, L.P.,"'Deflate' Compressed Data Format Specification".
//      Available in ftp.uu.net:/pub/archiving/zip/doc/deflate-1.1.doc
//
//      Storer, James A.
//          Data Compression:  Methods and Theory, pp. 49-50.
//          Computer Science Press, 1988.  ISBN 0-7167-8156-5.
//
//      Sedgewick, R.
//          Algorithms, p290.
//          Addison-Wesley, 1983. ISBN 0-201-06672-6.
//------------------------------------------------------------------------------
#include "lib/zlib/deflate.h"
#include "utils/macros.h"
namespace zlib {

#ifdef __clang__
  #pragma clang diagnostic push
  #pragma clang diagnostic ignored "-Wconversion"
  #pragma clang diagnostic ignored "-Wcomma"
  #pragma clang diagnostic ignored "-Wpadded"
  #pragma clang diagnostic ignored "-Wold-style-cast"
  #pragma clang diagnostic ignored "-Wsign-conversion"
  #pragma clang diagnostic ignored "-Wunused-const-variable"
  #pragma clang diagnostic ignored "-Wzero-as-null-pointer-constant"
#endif

#if DT_OS_WINDOWS
    #pragma warning(push)
    #pragma warning(disable : 4244)
#endif


/* ===========================================================================
 * Constants
 */

#define MAX_BL_BITS 7
/* Bit length codes must not exceed MAX_BL_BITS bits */

#define END_BLOCK 256
/* end of block literal code */

#define REP_3_6      16
/* repeat previous bit length 3-6 times (2 bits of repeat count) */

#define REPZ_3_10    17
/* repeat a zero length 3-10 times  (3 bits of repeat count) */

#define REPZ_11_138  18
/* repeat a zero length 11-138 times  (7 bits of repeat count) */

static const int extra_lbits[LENGTH_CODES] /* extra bits for each length code */
   = {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0};

static const int extra_dbits[D_CODES] /* extra bits for each distance code */
   = {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};

static const int extra_blbits[BL_CODES]/* extra bits for each bit length code */
   = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7};

static const uch bl_order[BL_CODES]
   = {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15};
/* The lengths of the bit length codes are sent in order of decreasing
 * probability, to avoid transmitting the lengths for unused bit length codes.
 */



/* ===========================================================================
 * Local data. These are initialized only once.
 */

#define DIST_CODE_LEN  512 /* see definition of array dist_code below */

#include "lib/zlib/trees.h"


struct static_tree_desc_s {
  const ct_data *static_tree;  /* static tree or NULL */
  const intf *extra_bits;      /* extra bits for each code or NULL */
  int     extra_base;          /* base index for extra_bits */
  int     elems;               /* max number of elements in the tree */
  int     max_length;          /* max bit length for the codes */
};

static const static_tree_desc  static_l_desc =
    {static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS};

static const static_tree_desc  static_d_desc =
    {static_dtree, extra_dbits, 0,          D_CODES, MAX_BITS};

static const static_tree_desc  static_bl_desc =
    {(const ct_data *)0, extra_blbits, 0,   BL_CODES, MAX_BL_BITS};



/* ===========================================================================
 * Local (static) routines in this file.
 */

static void init_block     (deflate_state *s);
static void pqdownheap     (deflate_state *s, ct_data *tree, int k);
static void gen_bitlen     (deflate_state *s, tree_desc *desc);
static void gen_codes      (ct_data *tree, int max_code, ushf *bl_count);
static void build_tree     (deflate_state *s, tree_desc *desc);
static void scan_tree      (deflate_state *s, ct_data *tree, int max_code);
static void send_tree      (deflate_state *s, ct_data *tree, int max_code);
static int  build_bl_tree  (deflate_state *s);
static void send_all_trees (deflate_state *s, int lcodes, int dcodes,
                            int blcodes);
static void compress_block (deflate_state *s, const ct_data *ltree,
                            const ct_data *dtree);
static int  detect_data_type(deflate_state *s);
static unsigned bi_reverse (unsigned value, int length);
static void bi_windup      (deflate_state *s);
static void bi_flush       (deflate_state *s);


#define send_code(s, c, tree) send_bits(s, tree[c].Code, tree[c].Len)
   /* Send a code of the given tree. c and tree must not have side effects */




/* ===========================================================================
 * Output a short LSB first on the stream.
 * IN assertion: there is enough room in pendingBuf.
 */
#define put_short(s, w) { \
  put_byte(s, (uch)((w) & 0xff)); \
  put_byte(s, (uch)((ush)(w) >> 8)); \
}



/* ===========================================================================
 * Send a value on a given number of bits.
 * IN assertion: length <= 16 and value fits in length bits.
 */
#define send_bits(s, value, length) \
{ int len = length;\
  if (s->bi_valid > (int)Buf_size - len) {\
  int val = (int)value;\
  s->bi_buf |= (ush)val << s->bi_valid;\
  put_short(s, s->bi_buf);\
  s->bi_buf = (ush)val >> (Buf_size - s->bi_valid);\
  s->bi_valid += len - Buf_size;\
  } else {\
  s->bi_buf |= (ush)(value) << s->bi_valid;\
  s->bi_valid += len;\
  }\
}




/* ===========================================================================
 * Initialize the tree data structures for a new zlib stream.
 */
void _tr_init(deflate_state *s)
{
  s->l_desc.dyn_tree = s->dyn_ltree;
  s->l_desc.stat_desc = &static_l_desc;

  s->d_desc.dyn_tree = s->dyn_dtree;
  s->d_desc.stat_desc = &static_d_desc;

  s->bl_desc.dyn_tree = s->bl_tree;
  s->bl_desc.stat_desc = &static_bl_desc;

  s->bi_buf = 0;
  s->bi_valid = 0;

  /* Initialize the first block of the first file: */
  init_block(s);
}



/* ===========================================================================
 * Initialize a new block.
 */
static void init_block(deflate_state *s)
{
  int n; /* iterates over tree elements */

  /* Initialize the trees. */
  for (n = 0; n < L_CODES;  n++) s->dyn_ltree[n].Freq = 0;
  for (n = 0; n < D_CODES;  n++) s->dyn_dtree[n].Freq = 0;
  for (n = 0; n < BL_CODES; n++) s->bl_tree[n].Freq = 0;

  s->dyn_ltree[END_BLOCK].Freq = 1;
  s->opt_len = s->static_len = 0L;
  s->last_lit = s->matches = 0;
}

#define SMALLEST 1
/* Index within the heap array of least frequent node in the Huffman tree */




/* ===========================================================================
 * Remove the smallest element from the heap and recreate the heap with
 * one less element. Updates heap and heap_len.
 */
#define pqremove(s, tree, top) \
  {\
    top = s->heap[SMALLEST]; \
    s->heap[SMALLEST] = s->heap[s->heap_len--]; \
    pqdownheap(s, tree, SMALLEST); \
  }



/* ===========================================================================
 * Compares to subtrees, using the tree depth as tie breaker when
 * the subtrees have equal frequency. This minimizes the worst case length.
 */
#define smaller(tree, n, m, depth) \
   (tree[n].Freq < tree[m].Freq || \
   (tree[n].Freq == tree[m].Freq && depth[n] <= depth[m]))



/* ===========================================================================
 * Restore the heap property by moving down the tree starting at node k,
 * exchanging a node with the smallest of its two sons if necessary, stopping
 * when the heap property is re-established (each father smaller than its
 * two sons).
 */
static void pqdownheap(deflate_state *s, ct_data *tree, int k)
{
  int v = s->heap[k];
  int j = k << 1;  /* left son of k */
  while (j <= s->heap_len) {
    /* Set j to the smallest of the two sons: */
    if (j < s->heap_len &&
      smaller(tree, s->heap[j+1], s->heap[j], s->depth)) {
      j++;
    }
    /* Exit if v is smaller than both sons */
    if (smaller(tree, v, s->heap[j], s->depth)) break;

    /* Exchange v with the smallest son */
    s->heap[k] = s->heap[j];  k = j;

    /* And continue down the tree, setting j to the left son of k */
    j <<= 1;
  }
  s->heap[k] = v;
}



/* ===========================================================================
 * Compute the optimal bit lengths for a tree and update the total bit length
 * for the current block.
 * IN assertion: the fields freq and dad are set, heap[heap_max] and
 *    above are the tree nodes sorted by increasing frequency.
 * OUT assertions: the field len is set to the optimal bit length, the
 *     array bl_count contains the frequencies for each bit length.
 *     The length opt_len is updated; static_len is also updated if stree is
 *     not null.
 */
static void gen_bitlen(deflate_state *s, tree_desc *desc)
{
  ct_data *tree        = desc->dyn_tree;
  int max_code         = desc->max_code;
  const ct_data *stree = desc->stat_desc->static_tree;
  const intf *extra    = desc->stat_desc->extra_bits;
  int base             = desc->stat_desc->extra_base;
  int max_length       = desc->stat_desc->max_length;
  int h;              /* heap index */
  int n, m;           /* iterate over the tree elements */
  int bits;           /* bit length */
  int xbits;          /* extra bits */
  ush f;              /* frequency */
  int overflow = 0;   /* number of elements with bit length too large */

  for (bits = 0; bits <= MAX_BITS; bits++) s->bl_count[bits] = 0;

  /* In a first pass, compute the optimal bit lengths (which may
   * overflow in the case of the bit length tree).
   */
  tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */

  for (h = s->heap_max+1; h < HEAP_SIZE; h++) {
    n = s->heap[h];
    bits = tree[tree[n].Dad].Len + 1;
    if (bits > max_length) bits = max_length, overflow++;
    tree[n].Len = (ush)bits;
    /* We overwrite tree[n].Dad which is no longer needed */

    if (n > max_code) continue; /* not a leaf node */

    s->bl_count[bits]++;
    xbits = 0;
    if (n >= base) xbits = extra[n-base];
    f = tree[n].Freq;
    s->opt_len += (ulg)f * (unsigned)(bits + xbits);
    if (stree) s->static_len += (ulg)f * (unsigned)(stree[n].Len + xbits);
  }
  if (overflow == 0) return;

  Tracev((stderr,"\nbit length overflow\n"));
  /* This happens for example on obj2 and pic of the Calgary corpus */

  /* Find the first bit length which could increase: */
  do {
    bits = max_length-1;
    while (s->bl_count[bits] == 0) bits--;
    s->bl_count[bits]--;      /* move one leaf down the tree */
    s->bl_count[bits+1] += 2; /* move one overflow item as its brother */
    s->bl_count[max_length]--;
    /* The brother of the overflow item also moves one step up,
     * but this does not affect bl_count[max_length]
     */
    overflow -= 2;
  } while (overflow > 0);

  /* Now recompute all bit lengths, scanning in increasing frequency.
   * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
   * lengths instead of fixing only the wrong ones. This idea is taken
   * from 'ar' written by Haruhiko Okumura.)
   */
  for (bits = max_length; bits != 0; bits--) {
    n = s->bl_count[bits];
    while (n != 0) {
      m = s->heap[--h];
      if (m > max_code) continue;
      if ((unsigned) tree[m].Len != (unsigned) bits) {
        Tracev((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits));
        s->opt_len += ((ulg)bits - tree[m].Len) * tree[m].Freq;
        tree[m].Len = (ush)bits;
      }
      n--;
    }
  }
}




/* ===========================================================================
 * Generate the codes for a given tree and bit counts (which need not be
 * optimal).
 * IN assertion: the array bl_count contains the bit length statistics for
 * the given tree and the field len is set for all tree elements.
 * OUT assertion: the field code is set for all tree elements of non
 *     zero code length.
 */
static void gen_codes(ct_data *tree, int max_code, ushf *bl_count)
{
  ush next_code[MAX_BITS+1]; /* next code value for each bit length */
  unsigned code = 0;         /* running code value */
  int bits;                  /* bit index */
  int n;                     /* code index */

  /* The distribution counts are first used to generate the code values
   * without bit reversal.
   */
  for (bits = 1; bits <= MAX_BITS; bits++) {
    code = (code + bl_count[bits-1]) << 1;
    next_code[bits] = (ush)code;
  }
  /* Check that the bit counts in bl_count are consistent. The last code
   * must be all ones.
   */
  Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1,
      "inconsistent bit counts");
  Tracev((stderr,"\ngen_codes: max_code %d ", max_code));

  for (n = 0;  n <= max_code; n++) {
    int len = tree[n].Len;
    if (len == 0) continue;
    /* Now reverse the bits */
    tree[n].Code = (ush)bi_reverse(next_code[len]++, len);

    Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
       n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1));
  }
}




/* ===========================================================================
 * Construct one Huffman tree and assigns the code bit strings and lengths.
 * Update the total bit length for the current block.
 * IN assertion: the field freq is set for all tree elements.
 * OUT assertions: the fields len and code are set to the optimal bit length
 *     and corresponding code. The length opt_len is updated; static_len is
 *     also updated if stree is not null. The field max_code is set.
 */
static void build_tree(deflate_state *s, tree_desc *desc)
{
  ct_data *tree         = desc->dyn_tree;
  const ct_data *stree  = desc->stat_desc->static_tree;
  int elems             = desc->stat_desc->elems;
  int n, m;          /* iterate over heap elements */
  int max_code = -1; /* largest code with non zero frequency */
  int node;          /* new node being created */

  /* Construct the initial heap, with least frequent element in
   * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
   * heap[0] is not used.
   */
  s->heap_len = 0, s->heap_max = HEAP_SIZE;

  for (n = 0; n < elems; n++) {
    if (tree[n].Freq != 0) {
      s->heap[++(s->heap_len)] = max_code = n;
      s->depth[n] = 0;
    } else {
      tree[n].Len = 0;
    }
  }

  /* The pkzip format requires that at least one distance code exists,
   * and that at least one bit should be sent even if there is only one
   * possible code. So to avoid special checks later on we force at least
   * two codes of non zero frequency.
   */
  while (s->heap_len < 2) {
    node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);
    tree[node].Freq = 1;
    s->depth[node] = 0;
    s->opt_len--; if (stree) s->static_len -= stree[node].Len;
    /* node is 0 or 1 so it does not have extra bits */
  }
  desc->max_code = max_code;

  /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
   * establish sub-heaps of increasing lengths:
   */
  for (n = s->heap_len/2; n >= 1; n--) pqdownheap(s, tree, n);

  /* Construct the Huffman tree by repeatedly combining the least two
   * frequent nodes.
   */
  node = elems;              /* next internal node of the tree */
  do {
    pqremove(s, tree, n);  /* n = node of least frequency */
    m = s->heap[SMALLEST]; /* m = node of next least frequency */

    s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */
    s->heap[--(s->heap_max)] = m;

    /* Create a new node father of n and m */
    tree[node].Freq = tree[n].Freq + tree[m].Freq;
    s->depth[node] = (uch)((s->depth[n] >= s->depth[m] ?
                s->depth[n] : s->depth[m]) + 1);
    tree[n].Dad = tree[m].Dad = (ush)node;
    #ifdef DUMP_BL_TREE
    if (tree == s->bl_tree) {
      fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)",
          node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
    }
    #endif
    /* and insert the new node in the heap */
    s->heap[SMALLEST] = node++;
    pqdownheap(s, tree, SMALLEST);

  } while (s->heap_len >= 2);

  s->heap[--(s->heap_max)] = s->heap[SMALLEST];

  /* At this point, the fields freq and dad are set. We can now
   * generate the bit lengths.
   */
  gen_bitlen(s, (tree_desc *)desc);

  /* The field len is now set, we can generate the bit codes */
  gen_codes ((ct_data *)tree, max_code, s->bl_count);
}




/* ===========================================================================
 * Scan a literal or distance tree to determine the frequencies of the codes
 * in the bit length tree.
 */
static void scan_tree (deflate_state *s, ct_data *tree, int max_code)
{
  int n;                     /* iterates over all tree elements */
  int prevlen = -1;          /* last emitted length */
  int curlen;                /* length of current code */
  int nextlen = tree[0].Len; /* length of next code */
  int count = 0;             /* repeat count of the current code */
  int max_count = 7;         /* max repeat count */
  int min_count = 4;         /* min repeat count */

  if (nextlen == 0) max_count = 138, min_count = 3;
  tree[max_code+1].Len = (ush)0xffff; /* guard */

  for (n = 0; n <= max_code; n++) {
    curlen = nextlen; nextlen = tree[n+1].Len;
    if (++count < max_count && curlen == nextlen) {
      continue;
    } else if (count < min_count) {
      s->bl_tree[curlen].Freq += count;
    } else if (curlen != 0) {
      if (curlen != prevlen) s->bl_tree[curlen].Freq++;
      s->bl_tree[REP_3_6].Freq++;
    } else if (count <= 10) {
      s->bl_tree[REPZ_3_10].Freq++;
    } else {
      s->bl_tree[REPZ_11_138].Freq++;
    }
    count = 0; prevlen = curlen;
    if (nextlen == 0) {
      max_count = 138, min_count = 3;
    } else if (curlen == nextlen) {
      max_count = 6, min_count = 3;
    } else {
      max_count = 7, min_count = 4;
    }
  }
}




/* ===========================================================================
 * Send a literal or distance tree in compressed form, using the codes in
 * bl_tree.
 */
static void send_tree (deflate_state *s, ct_data *tree, int max_code)
{
  int n;                     /* iterates over all tree elements */
  int prevlen = -1;          /* last emitted length */
  int curlen;                /* length of current code */
  int nextlen = tree[0].Len; /* length of next code */
  int count = 0;             /* repeat count of the current code */
  int max_count = 7;         /* max repeat count */
  int min_count = 4;         /* min repeat count */

  /* tree[max_code+1].Len = -1; */  /* guard already set */
  if (nextlen == 0) max_count = 138, min_count = 3;

  for (n = 0; n <= max_code; n++) {
    curlen = nextlen; nextlen = tree[n+1].Len;
    if (++count < max_count && curlen == nextlen) {
      continue;
    } else if (count < min_count) {
      do { send_code(s, curlen, s->bl_tree); } while (--count != 0);

    } else if (curlen != 0) {
      if (curlen != prevlen) {
        send_code(s, curlen, s->bl_tree); count--;
      }
      Assert(count >= 3 && count <= 6, " 3_6?");
      send_code(s, REP_3_6, s->bl_tree); send_bits(s, count-3, 2);

    } else if (count <= 10) {
      send_code(s, REPZ_3_10, s->bl_tree); send_bits(s, count-3, 3);

    } else {
      send_code(s, REPZ_11_138, s->bl_tree); send_bits(s, count-11, 7);
    }
    count = 0; prevlen = curlen;
    if (nextlen == 0) {
      max_count = 138, min_count = 3;
    } else if (curlen == nextlen) {
      max_count = 6, min_count = 3;
    } else {
      max_count = 7, min_count = 4;
    }
  }
}




/* ===========================================================================
 * Construct the Huffman tree for the bit lengths and return the index in
 * bl_order of the last bit length code to send.
 */
static int build_bl_tree(deflate_state *s)
{
  int max_blindex;  /* index of last bit length code of non zero freq */

  /* Determine the bit length frequencies for literal and distance trees */
  scan_tree(s, (ct_data *)s->dyn_ltree, s->l_desc.max_code);
  scan_tree(s, (ct_data *)s->dyn_dtree, s->d_desc.max_code);

  /* Build the bit length tree: */
  build_tree(s, (tree_desc *)(&(s->bl_desc)));
  /* opt_len now includes the length of the tree representations, except
   * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
   */

  /* Determine the number of bit length codes to send. The pkzip format
   * requires that at least 4 bit length codes be sent. (appnote.txt says
   * 3 but the actual value used is 4.)
   */
  for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) {
    if (s->bl_tree[bl_order[max_blindex]].Len != 0) break;
  }
  /* Update opt_len to include the bit length tree and counts */
  s->opt_len += 3*((ulg)max_blindex+1) + 5+5+4;
  Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld",
      s->opt_len, s->static_len));

  return max_blindex;
}



/* ===========================================================================
 * Send the header for a block using dynamic Huffman trees: the counts, the
 * lengths of the bit length codes, the literal tree and the distance tree.
 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
 */
static void send_all_trees(deflate_state *s, int lcodes, int dcodes, int blcodes)
{
  int rank;                    /* index in bl_order */

  Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
  Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES,
      "too many codes");
  Tracev((stderr, "\nbl counts: "));
  send_bits(s, lcodes-257, 5); /* not +255 as stated in appnote.txt */
  send_bits(s, dcodes-1,   5);
  send_bits(s, blcodes-4,  4); /* not -3 as stated in appnote.txt */
  for (rank = 0; rank < blcodes; rank++) {
    Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
    send_bits(s, s->bl_tree[bl_order[rank]].Len, 3);
  }
  Tracev((stderr, "\nbl tree: sent %ld", s->bits_sent));

  send_tree(s, (ct_data *)s->dyn_ltree, lcodes-1); /* literal tree */
  Tracev((stderr, "\nlit tree: sent %ld", s->bits_sent));

  send_tree(s, (ct_data *)s->dyn_dtree, dcodes-1); /* distance tree */
  Tracev((stderr, "\ndist tree: sent %ld", s->bits_sent));
}



/* ===========================================================================
 * Send a stored block
 */
void _tr_stored_block(
  deflate_state *s,
  charf *buf,
  ulg stored_len,
  int last
) {
  send_bits(s, (STORED_BLOCK<<1)+last, 3);    /* send block type */
  bi_windup(s);        /* align on byte boundary */
  put_short(s, (ush)stored_len);
  put_short(s, (ush)~stored_len);
  zmemcpy(s->pending_buf + s->pending, (Bytef *)buf, stored_len);
  s->pending += stored_len;
}



/* ===========================================================================
 * Flush the bits in the bit buffer to pending output (leaves at most 7 bits)
 */
void _tr_flush_bits(deflate_state *s)
{
  bi_flush(s);
}



/* ===========================================================================
 * Send one empty static block to give enough lookahead for inflate.
 * This takes 10 bits, of which 7 may remain in the bit buffer.
 */
void _tr_align(deflate_state *s)
{
  send_bits(s, STATIC_TREES<<1, 3);
  send_code(s, END_BLOCK, static_ltree);
  bi_flush(s);
}



/* ===========================================================================
 * Determine the best encoding for the current block: dynamic trees, static
 * trees or store, and write out the encoded block.
 */
void _tr_flush_block(
  deflate_state *s,
  charf *buf,
  ulg stored_len,
  int last
) {
  ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
  int max_blindex = 0;  /* index of last bit length code of non zero freq */

  /* Build the Huffman trees unless a stored block is forced */
  if (s->level > 0) {

    /* Check if the file is binary or text */
    if (s->strm->data_type == Z_UNKNOWN)
      s->strm->data_type = detect_data_type(s);

    /* Construct the literal and distance trees */
    build_tree(s, (tree_desc *)(&(s->l_desc)));
    Tracev((stderr, "\nlit data: dyn %ld, stat %ld", s->opt_len,
        s->static_len));

    build_tree(s, (tree_desc *)(&(s->d_desc)));
    Tracev((stderr, "\ndist data: dyn %ld, stat %ld", s->opt_len,
        s->static_len));
    /* At this point, opt_len and static_len are the total bit lengths of
     * the compressed block data, excluding the tree representations.
     */

    /* Build the bit length tree for the above two trees, and get the index
     * in bl_order of the last bit length code to send.
     */
    max_blindex = build_bl_tree(s);

    /* Determine the best encoding. Compute the block lengths in bytes. */
    opt_lenb = (s->opt_len+3+7)>>3;
    static_lenb = (s->static_len+3+7)>>3;

    Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
        opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
        s->last_lit));

    if (static_lenb <= opt_lenb) opt_lenb = static_lenb;

  } else {
    Assert(buf != (char*)0, "lost buf");
    opt_lenb = static_lenb = stored_len + 5; /* force a stored block */
  }

  #ifdef FORCE_STORED
    if (buf != (char*)0) { /* force stored block */
  #else
    if (stored_len+4 <= opt_lenb && buf != (char*)0) {
               /* 4: two words for the lengths */
  #endif
    /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
     * Otherwise we can't have processed more than WSIZE input bytes since
     * the last block flush, because compression would have been
     * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
     * transform a block into a stored block.
     */
    _tr_stored_block(s, buf, stored_len, last);

  #ifdef FORCE_STATIC
    } else if (static_lenb >= 0) { /* force static trees */
  #else
    } else if (s->strategy == Z_FIXED || static_lenb == opt_lenb) {
  #endif
    send_bits(s, (STATIC_TREES<<1)+last, 3);
    compress_block(s, (const ct_data *)static_ltree,
             (const ct_data *)static_dtree);
  } else {
    send_bits(s, (DYN_TREES<<1)+last, 3);
    send_all_trees(s, s->l_desc.max_code+1, s->d_desc.max_code+1,
             max_blindex+1);
    compress_block(s, (const ct_data *)s->dyn_ltree,
             (const ct_data *)s->dyn_dtree);
  }
  Assert (s->compressed_len == s->bits_sent, "bad compressed size");
  /* The above check is made mod 2^32, for files larger than 512 MB
   * and uLong implemented on 32 bits.
   */
  init_block(s);

  if (last) {
    bi_windup(s);
  }
  Tracev((stderr,"\ncomprlen %lu(%lu) ", s->compressed_len>>3,
       s->compressed_len-7*last));
}



/* ===========================================================================
 * Save the match info and tally the frequency counts. Return true if
 * the current block must be flushed.
 */
int _tr_tally (deflate_state *s, unsigned dist, unsigned lc)
{
  s->d_buf[s->last_lit] = (ush)dist;
  s->l_buf[s->last_lit++] = (uch)lc;
  if (dist == 0) {
    /* lc is the unmatched char */
    s->dyn_ltree[lc].Freq++;
  } else {
    s->matches++;
    /* Here, lc is the match length - MIN_MATCH */
    dist--;             /* dist = match distance - 1 */
    Assert((ush)dist < (ush)MAX_DIST(s) &&
         (ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) &&
         (ush)d_code(dist) < (ush)D_CODES,  "_tr_tally: bad match");

    s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
    s->dyn_dtree[d_code(dist)].Freq++;
  }

  #ifdef TRUNCATE_BLOCK
    /* Try to guess if it is profitable to stop the current block here */
    if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
      /* Compute an upper bound for the compressed length */
      ulg out_length = (ulg)s->last_lit*8L;
      ulg in_length = (ulg)((long)s->strstart - s->block_start);
      int dcode;
      for (dcode = 0; dcode < D_CODES; dcode++) {
        out_length += (ulg)s->dyn_dtree[dcode].Freq *
          (5L+extra_dbits[dcode]);
      }
      out_length >>= 3;
      Tracev((stderr,"\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
           s->last_lit, in_length, out_length,
           100L - out_length*100L/in_length));
      if (s->matches < s->last_lit/2 && out_length < in_length/2) return 1;
    }
  #endif
  return (s->last_lit == s->lit_bufsize-1);
  /* We avoid equality with lit_bufsize because of wraparound at 64K
   * on 16 bit machines and because stored blocks are restricted to
   * 64K-1 bytes.
   */
}



/* ===========================================================================
 * Send the block data compressed using the given Huffman trees
 */
static void compress_block(
  deflate_state *s,
  const ct_data *ltree,
  const ct_data *dtree
) {
  unsigned dist;      /* distance of matched string */
  int lc;             /* match length or unmatched char (if dist == 0) */
  unsigned lx = 0;    /* running index in l_buf */
  unsigned code;      /* the code to send */
  int extra;          /* number of extra bits to send */

  if (s->last_lit != 0) do {
    dist = s->d_buf[lx];
    lc = s->l_buf[lx++];
    if (dist == 0) {
      send_code(s, lc, ltree); /* send a literal byte */
      Tracecv(isgraph(lc), (stderr," '%c' ", lc));
    } else {
      /* Here, lc is the match length - MIN_MATCH */
      code = _length_code[lc];
      send_code(s, code+LITERALS+1, ltree); /* send the length code */
      extra = extra_lbits[code];
      if (extra != 0) {
        lc -= base_length[code];
        send_bits(s, lc, extra);       /* send the extra length bits */
      }
      dist--; /* dist is now the match distance - 1 */
      code = d_code(dist);
      Assert (code < D_CODES, "bad d_code");

      send_code(s, code, dtree);       /* send the distance code */
      extra = extra_dbits[code];
      if (extra != 0) {
        dist -= (unsigned)base_dist[code];
        send_bits(s, dist, extra);   /* send the extra distance bits */
      }
    } /* literal or match pair ? */

    /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
    Assert((uInt)(s->pending) < s->lit_bufsize + 2*lx,
         "pendingBuf overflow");

  } while (lx < s->last_lit);

  send_code(s, END_BLOCK, ltree);
}



/* ===========================================================================
 * Check if the data type is TEXT or BINARY, using the following algorithm:
 * - TEXT if the two conditions below are satisfied:
 *    a) There are no non-portable control characters belonging to the
 *       "black list" (0..6, 14..25, 28..31).
 *    b) There is at least one printable character belonging to the
 *       "white list" (9 {TAB}, 10 {LF}, 13 {CR}, 32..255).
 * - BINARY otherwise.
 * - The following partially-portable control characters form a
 *   "gray list" that is ignored in this detection algorithm:
 *   (7 {BEL}, 8 {BS}, 11 {VT}, 12 {FF}, 26 {SUB}, 27 {ESC}).
 * IN assertion: the fields Freq of dyn_ltree are set.
 */
static int detect_data_type(deflate_state *s)
{
  /* black_mask is the bit mask of black-listed bytes
   * set bits 0..6, 14..25, and 28..31
   * 0xf3ffc07f = binary 11110011111111111100000001111111
   */
  unsigned long black_mask = 0xf3ffc07fUL;
  int n;

  /* Check for non-textual ("black-listed") bytes. */
  for (n = 0; n <= 31; n++, black_mask >>= 1)
    if ((black_mask & 1) && (s->dyn_ltree[n].Freq != 0))
      return Z_BINARY;

  /* Check for textual ("white-listed") bytes. */
  if (s->dyn_ltree[9].Freq != 0 || s->dyn_ltree[10].Freq != 0
      || s->dyn_ltree[13].Freq != 0)
    return Z_TEXT;
  for (n = 32; n < LITERALS; n++)
    if (s->dyn_ltree[n].Freq != 0)
      return Z_TEXT;

  /* There are no "black-listed" or "white-listed" bytes:
   * this stream either is empty or has tolerated ("gray-listed") bytes only.
   */
  return Z_BINARY;
}



/* ===========================================================================
 * Reverse the first len bits of a code, using straightforward code (a faster
 * method would use a table)
 * IN assertion: 1 <= len <= 15
 */
static unsigned bi_reverse(unsigned code, int len)
{
  unsigned res = 0;
  do {
    res |= code & 1;
    code >>= 1;
    res <<= 1;
  } while (--len > 0);
  return res >> 1;
}



/* ===========================================================================
 * Flush the bit buffer, keeping at most 7 bits in it.
 */
static void bi_flush(deflate_state *s)
{
  if (s->bi_valid == 16) {
    put_short(s, s->bi_buf);
    s->bi_buf = 0;
    s->bi_valid = 0;
  } else if (s->bi_valid >= 8) {
    put_byte(s, (Byte)s->bi_buf);
    s->bi_buf >>= 8;
    s->bi_valid -= 8;
  }
}



/* ===========================================================================
 * Flush the bit buffer and align the output on a byte boundary
 */
static void bi_windup(deflate_state *s)
{
  if (s->bi_valid > 8) {
    put_short(s, s->bi_buf);
  } else if (s->bi_valid > 0) {
    put_byte(s, (Byte)s->bi_buf);
  }
  s->bi_buf = 0;
  s->bi_valid = 0;
}


#ifdef __clang__
  #pragma clang diagnostic pop
#endif

#if DT_OS_WINDOWS
    #pragma warning(pop)
#endif


}  // namespace zlib
